I then shouted into M [the mouthpiece] the following sentence: “Mr. Watson, come here — I want to see you.” To my delight he came and declared that he had heard and understood what I said.

I asked him to repeat the words. He answered, “You said ‘Mr. Watson — come here — I want to see you.'” We then changed places and I listened at S [the speaker] while Mr. Watson read a few passages from a book into the mouthpiece M. It was certainly the case that articulate sounds proceeded from S. The effect was loud but indistinct and muffled.

That disagreement, though, is trifling compared to the long controversy over whether Bell truly invented the telephone. Another inventor, Elisha Gray, was working on a similar device, and recent books claim that Bell not only stole Gray’s ideas, but may even have bribed a patent examiner to let him sneak a look at Gray’s filing.

After years of litigation, Bell’s patents eventually withstood challenges from Gray and others — perhaps by right, perhaps by virtue of bigger backers and better barristers. In that respect, the controversy recalls the patent battle over the telegraph and foreshadows later squabbles over the automobile, the airplane, the spreadsheet, online shopping carts, web-auction software, and the look and feel of operating systems.

One thing we know for sure: Mr. Watson was at work that day in Bell’s lab. The telephone call did not interrupt his dinner with a special offer for home repairs or timeshare vacations in Florida.